Method of making a disposable unitary cytology chamber and filter card for centrifugation of fluid samples

ABSTRACT

A unitary disposable chamber and filter unit including a method for making same in which a support surface on the chamber has energy directors such that when ultrasonic energy is applied thereto the energy directors will become molten and bond a filter card to the support surface at spaced locations away from the point of discharge of the fluid through the filter card onto a microscopic slide or other surface for analysis.

REFERENCE TO CROSS-RELATED APPLICATION

This application is a divisional application of Ser. No. 678,262, filedDec. 5, 1984, now U.S. Pat. No. 4,678,579, granted 7/7/87, forDISPOSABLE UNITARY CYTOLOGY CHAMBER AND FILTER CARD FOR CENTRIFUGATIONOF FLUID SAMPLES AND METHOD OF MAKING SAME, by Daniel V. Griffin.

This invention relates to filter assemblies for use in the analysis ofbody fluids; and more particularly relates to a novel and improvedunitary cytology chamber and filter card and to a method for making samefor use in the centrifugation of body fluid samples.

BACKGROUND AND FIELD OF THE INVENTION

Centrifuges are customarily employed in the separation of cells andother solids from body fluids to permit subsequent diagnosis oranalysis. Centrifuges presently in use are designed to accommodate aplurality of sample chambers and in such a way as to be capable ofrapidly loading and unloading the chambers so as to facilitate morerapid and efficient sampling. One such centrifuge is the cytocentrifugeset forth and disclosed in U.S. Pat. No. 4,391,710 to A. J. Gordonwherein a plurality of holders are arranged in spaced circumferentialrelation to one another about a common motor drive, each holder adaptedto retain an individual chamber together with a separate filter card andslide. Specifically, each holder is made up of a channel adapted toreceive a slide which is overlaid by a filter card and by acorrespondingly shaped end flange at an end of the sample chamber. Theholder includes a clamp in order to retain the assembly of the chamber,filter card and s1ide together and in properly aligned relation suchthat the filter card will properly absorb the liquid component of thesample and permit the cells and other solids to pass through the cardand be deposited onto a surface of the slide.

As noted in the hereinbefore referred to patent to Gordon, the problemassociated with prior art arrangements is the assembly operation to becarried out in the installation of the sample chambers in conjunctionwith the rotating carrier of the centrifuge and specifically to achieveproper alignment between the chamber, filter card and receiving surfaceof the slides. Such arrangements in the past have been difficult toassemble and manipulate especially when the material being centrifugedmust be handled under conditions of containment in order to prevent theescape of toxic or noxious matter. Nevertheless, in accordance with theteachings of the patent to Gordon, it is necessary to preassemble eachchamber, filter card and slide as a preliminary to mounting in theholder, Upon completion of the centrifuge operation, removal of theassembled components and disassembly of same to recover the sample to beexamined, the holders and chambers must then be cleaned and sterilizedindividually for subsequent reuse.

Notwithstanding that the centrifuge disclosed in the patent to Gordonoffers definite advantages and improvements over the prior art in thehandling and sampling of body fluids, there exists the need for aunitary cytology chamber and filter card assembly which not onlyminimizes the steps of preassembly with the microscopic slide or glassas a preliminary to placement in the holder, but assures accuratealignment between the elements and, most importantly, precludes reuse ofthe chamber and filter card. The latter is particularly important in thehandling of body fluids containing certain diseases where it is vitalthat the chamber or filter card not be reused after a particularsampling operation. Joining of the two components together as a unitaryassembly avoids any temptation on the part of the operator to reuseeither or both in subsequent sampling operations. It is thereforeproposed to provide a unitary chamber and filter card in which thecomponents are permanently united together in properly aligned relationand cannot be separated without destroying the interface between thetwo; yet in uniting the two together avoids any danger of contaminationof the sample and offers an extremely simple but effective way ofassembling the components so as to prevent their reuse and assure morerapid loading and unloading of the samples with respect to theirrespective holders.

Other representative U.S. Letters Pat. in this field are U.S. Pat. Nos.4,265,762 to D. L. Brenholt; 4,344,562 to A. Ricci; and 4,357,240 to R.C. Mehra et al. However, none suggests or discloses a manner and meansby which a filter card may be permanently affixed to an end flange on achamber and in properly aligned relation so as to form a disposable unitand in such a way as to preclude reuse of the assembly in the mannerdevised according to the present invention.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide for anovel and improved disposable cytology chamber for use in analysis ofliquid samples.

Another object of the present invention is to provide for a novel andimproved method and means for fabricating a unitary, disposable cytologychamber and filter card so as to prevent reuse of the chamber togetherwith a vented cap to prevent spillage of liquid during centrifugeoperations.

It is a further object of the present invention to provide for a noveland improved method of integrally uniting a filter card to a flat endsurface or flange of a chamber in such a way as to avoid the possiblecontamination by use of adhesives or other securing means and to assurereliable performance in operation.

It is an additional object of the present invention to provide for anovel and improved method of ultrasonically welding a filter card to aflat end surface of a disposable chamber unit in such a way as to avoidcontamination of a fluid sample to be analyzed and to prevent reuse of aunit.

In accordance with the present invention there has been devised acytology chamber characterized by having a funnel-shaped portion andcommunicating discharge port which extends through an end flange, and afilter card is permanently affixed to the exposed end surface of theflange with an opening in the filter card properly aligned with thedischarge port. The end surface is characterized by having specialattachment means to facilitate permanent attachment of the filter cardto the end surface without in any manner altering the characteristics ofthe filter card itself for its intended purposes. In the method of thepresent invention, a filter card is permanently affixed to a flat endflange of a cytology chamber wherein the chamber has a funnel anddischarge port which intercommunicates between the funnel and endflange, the steps comprising forming energy directors in the form ofprotruding ribs on the exposed surface of the end flange andultrasonically welding one surface of the filter card whereby to embedand fix the energy directors in the card at selected spaced intervalsaway from the discharge port while assuring that the card will bedisposed in flush relation to the end flange and conduct liquid byabsorption away from the discharge port when the chamber is subjected tocentrifugal forces.

In a preferred embodiment, the cytology chamber and attached filter cardare combined with a microscopic slide which is applied in flush relationto the filter card and releasably clamped in a holder of acytocentrifuge. The cytology chamber is of the type having a generallyfunnel-shaped portion disposed on a longitudinal axis parallel to theaxis of rotation of the centrifuge, a releasable cap usable incombination with vents in the funnel and a discharge port at one end ofthe funnel extending radially away from the funnel into communicationwith the end flange. Thus, when a liquid sample is placed in the funneland subjected to centrifugal forces it will be constrained to flowoutwardly through the discharge port where the liquid component of thesample is absorbed by the filter card and any solid matter is collectedon a surface of the slide. The chamber and slide are then released fromthe holder and the specimen on the slide subjected to diagnosis oranalysis in a conventional manner. The permanent attachment of thefilter card to the end flange of the chamber is such, that any attemptto remove the filter card will result in leaving substantial segments ofthe card in attached relation to the energy director and preventreplacement with another card.

Other objects, advantages and features of the present invention willbecome more readily appreciated and understood when taken together withthe following detailed description in conjunction with the accompanyingdrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating the disposition andmounting of a preferred form of chamber and filter card assembly in acytocentrifuge in accordance with the present invention;

FIG. 2 is an exploded view of a preferred form of cytology chamber andfilter card preliminary to ultrasonically welding the filter card to theend surface of the chamber;

FIG. 3 is a top plan view of the assembled cytology chamber and fi1tercard as shown in FIG. 2;

FIG. 4 is a front view of the cytology chamber and illustrated in dottedform the placement of energy directors on the end surface thereof;

FIG. 5 is a cross-sectional view taken about lines 5--5 of FIG. 4;

FIG. 6 is a somewhat perspective view illustrating a welding unitemployed in assembling a filter card and cytology chamber together;

FIG. 7 is an enlarged view in more detail of the welding unitillustrated in FIG. 6 and with the welding horn shown partially insection;

FIG. 8 is a view taken about lines 8--8 of FIG. 7 and illustrating theplacement of the filter card on a portion of a jig; and

FIG. 9 is an end view partially in section of the welder unit and jigshown in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring in more detail to the drawings, there is shown by way ofillustrative example in FIG. 1 a preferred form of chamber and filtercard assembly 10 installed in a holder 12 of a cytocentrifuge, a portionof which is generally designated at 14. As a setting for the presentinvention, the centrifuge 14 comprises a series of holders 12 which aremounted in spaced circumferential relation in a common carrier plate 16which is disposed for rotation about a vertical axis through a centraldrive unit including a hub, a portion of which is represented at 18. Forpurposes of illustration, the drive unit may be suitably comprised ofthe central hub 18 mounted on the output shaft of a drive motor, and thecarrier plate is fixed for rotation to the hub 18. The holder assemblies10 and carrier plate 16 are suspended within a lower bowl portion 20 andupper cover 21 with mating peripheral edges 22 and 23 of the bowl 20 andcover 21 interconnected and a seal 24 being interposed therebetween.

As a pre1iminary to describing the construction of a typical holder 12,it should be noted that the preferred form of cytology chamber 10comprises a main body in the form of a flat, generally rectangular plate28 having an end flange 30 disposed normal to and along one edge of theplate 28 and which is reinforced by generally triangular, upper andlower ends 31 and 32, respectively. The front surface of the flange 30is provided with horizontally directed, slotted ledges 33 on oppositesides of the plate 28 for a purpose to be described. A verticallydirected funnel portion 34 is contained within the body and tapersdownwardly into a laterally extending discharge port 36 which isdirected from the lower end of the funnel through the end flange 30 andterminates in an opening 37 surrounded by an annular sealing surface 38projecting from exposed end surface 30' of the end flange 30. A cap 39is dimensioned for releasable insertion in the upper open end of thefunnel, and release vents in the form of vertical slots 35 along theinner wall of the funnel permit the escape of air when the cap 39 is inplace. A filter card 40 is dimensioned to be coextensive with the endflange 30 and is provided with a circular opening 42 which is located toregister with the annular sealing surface 38 when the filter card isaligned with and permanently attached to the end flange.

Broadly, cytology chambers of the type described are designed such thata liquid sample may be placed in the funnel 34 and remain there untilthe centrifuging operation commences at which time the sample will bedriven in a radial outward direction through the discharge port 36. Forthis purpose, the holder assembly 12 is constructed and arranged forreleasable insertion and clamping of the chamber therein with the funnelportion 34 positioned radially inwardly of the end flange 30 and withthe funnel 34 disposed in a generally upright position. The holderassembly 12 is comprised of a generally U-shaped channel 46 havingopposite side plates 47, a common web 48 interconnecting the sideplates, and a locating lug or end stop 49. A generally U-shaped clampingmember 50 is disposed in surrounding relation to the midsection of theclamping member, the clamping member having opposite, generallytriangular sidewalls 52 with inturned lugs 53 at the lower extremitiesof the sidewalls 52 to overlie the downwardly tapered sides 47 of thechannel 46 and engage the ledges 33. A pivot rod 54 extends across thechannel member 50 through the sidewalls 52 and is spring-loaded by atorsion spring 55 so as to permit rocking movement of the clamp 50relative to the channel 46 in a manner to be described. A release screw58 is threaded into a boss 59 on the clamping member 50 so that itsleading end is engageable with the rear face of the web 48 of thechannel to cause the clamping member 50 to rock or tilt about the pivotrod 54 in opposition to the torsion of the spring element 55 on thepivot rod.

In the installation of the chamber assembly into the holder assembly, amicroscopic slide 60 is assembled or placed against the filter card 40.Preferably, the slide 60 is a rectangular glass slide dimensioned tocorrespond to the size of the filter card 40 and is inserted along withthe filter card 40 and end flange 30 of the chamber by slidingdownwardly through the channel 46 until the lower edges of the endflange 30, filter card 40 and slide 60 abut the forwardly directed endstop 49 at the lower edge of the channel 46. In this relation, theinturned lugs 53 wi11 engage opposite sides of the end flange 30. In theinloading position prior to commencement of the centrifuging operation,while forming no part of the present invention, the release screw 58 inbearing against the channel member 46 will cause the chamber 10 and itsfunnel 34 to be tilted or tipped somewhat downwardly and the open end ofthe port to be tipped upwardly so that any liquid in the funnel whichpasses into the discharge port 46 will remain at the closed end of theport. Under rotation, the centrifugal force imparted to the holder willcause the holder and chamber assembly to rock back into a horizontalposition as illustrated and simultaneously to force the liquid to flowfrom the funnel through the discharge port and through the matchedopenings at the open end of the discharge port and the filter card intodirect contact with the exposed surface of the slide. The filter cardwill absorb any of the liquid contents of the sample whiIe any solidmatter will be deposited on the surface of the slide.

Having considered the manner in which the chamber assembly 10 isemployed in the recovery of a sample, reference is now made in moredetail to the construction and arrangement of the end flange 30 andfilter card 40 and the method of joining or permanently affixing thefilter card to the end flange. Referring specifically to FIGS. 2 to 5,the normally exposed end surface 31 of the end flange 30 is formed withnarrow elongated ribs 60 which protrude a limited distance away from theend surface 31 and converge into tapered or pointed edges 62. Each rib60 is located to extend in closely spaced parallel relation to oppositeside edges of the end flange 31 and to protrude outwardly therefrom fora limited distance which is less than the thickness of the filter card40. Similarly, the annular sealing flange or surface 38 is formed insurrounding relation to the open end of the port 36 and protrudes fromthe end surface a distance slightly greater than that of the ribs.Preferably, the ribs are formed out of the material on the end flange,each preferably being of a length of approximately one-fifth of thetotal length of the end flange and located relatively near the fourcorners of the end flange but away from the central opening. The ribs asdescribed define energy directors to facilitate attachment of the filtercard thereto when subjected to ultrasonic welding.

In the preferred method of joining the filter card 40 to the end flange30, welding is accomplished by application of frequencies in theultrasonic range while simultaneously pressing the filter card againstthe end flange whereby the ultrasonic energy is concentrated at thetapered edges 62 to cause them to become molten and to bond firmly tothe paper filter. In this way, the ribs are locked or firmly embeddedinto the surface of the filter card without otherwise altering thecharacteristics of the filter. The mere application of ultrasonicwelding is insufficient to secure the filter card to the end flangewithout energy directors at appropriately spaced intervals which serveto permanently affix or attach the filter card to the end flange asdescribed. This form of positive attachment achieves more accuratealignment between the card and end flange so as to assure that theopenings between the port and filter card are aligned for unobstructedflow of the liquid therethrough and greatly facilitates loading of thechamber and attached filter card in place within the holder assemblypreliminary to each centrifuge operation. Most importantly, the attachedfilter card avoids reuse of the card or assembly, since any attempt toremove the filter card will leave substantial segments in surroundingrelation to the ribs and preclude proper placement and positioning of afresh filter card over the end flange of the chamber. Attachment in themanner described also minimizes any danger of smearing or loss of thedeposit on the slide when the holder assembly is removed from thecarrier plate and the slide is separated from the filter card andchamber for analysis.

In the preferred method of welding and affixing a filter card 40 to anend flange 30 of chamber 10, as illustrated in FIGS. 6 to 9, the chamber10 is inserted within a cavity 65 of a welding horn 80. A filter card 40is placed into position on a jig 82 beneath the exposed or lower endsurface of the flange 30. The welding horn 80 is specifically designedto be of generally U-shaped configuration with downwardly directed legs67 terminating in lower end surfaces 68, the horn 80 being superimposedover the chamber 10 until the end surfaces 68 are disposed in closeproximity to the front or upper surface of the end flange 30 on the sideopposite to the filter card 40. Slots 70 are formed in the end surfaces68 of the horn 80 to register with the ledges 33 on the end flange 30thereby permitting the end surfaces 68 of the horn to bear against theflat surface of the flange. Ultrasonic energy is then applied to thehorn via a standard welding unit as generally designated at W for a veryshort duration or interval of time on the order of less than one secondwhich is more than sufficient to heat the energy directors 60 to a leveland to cause their edges 62 to become molten and to bond to the filterwithout burning the filter paper. The horn is then removed followed byremoval of the completed chamber assembly from the cavity. A preferredform of ultrasonic welder is a Model 8400 horn with a gold boostermanufactured and sold by Branson Sonic Power Company of Dansbury, Conn.It should be appreciated that the tapered edges 62 of the energydirectors or ribs 60 permit sufficient concentration of heat to causethe edges to be rapidly heated to a molten state without burning thefilter paper itself. In this relation, other cross-sectionalconfigurations may be adopted or employed to accomplish the same end;and, for example, the cross-sectional configuration of the ribs may berounded or provided with multiple edges so long as there is sufficientcpncentration of heat to cause the desired bonding without undulyheating the paper filter. Moreover, the location of the ribs may bevaried to some extent, bearing in mind that the ultrasonic welder mustbe applied to the surface of the end flange directly opposite to theribs in order to most rapidly direct the energy into the ribs 60 forwelding purposes and therefore are most desirably located along oppositeside edges so as to be aligned opposite to the points of contact betweenthe ribs 60 and filter card 40.

It is therefore to be understood that various modifications and changesmay be made in the unitary chamber and filter unit and method of makingsame without departing from the spirit and scope of the presentinvention as defined by the appended claims.

I claim:
 1. The method of forming a unitary, disposable chamber and filter unit in which a chamber is provded with a liquid sample inlet and a discharge port which communicates between said inlet and an end flange, and a filter card is adapted to be positioned on said end flange with an opening therein aligned with said discharge port, the steps comprising:forming energy directors in the form of protruding ribs on a flat surface of said end flange; placing a filter card in overlying relation to said end flange with the opening in said filter card aligned with a discharge port; and applying ultrasonic energy to said end flange whereby to weld said energy directors to said filter cards.
 2. The method according to claim 1, wherein said energy directors are spaced along opposite sides of said end surface supporting said filter card and characterized by the steps of concentrating applications of ultrasonic energy to a surface of said end flange opposite to said energy directors.
 3. The method according to claim 1, including the step of forming said energy directors as generally triangular ribs which terminate in tapered edges in facing relation to said filter card.
 4. The method according to claim 1, characterized by the step of locating said energy directors at spaced intervals around the outer edge of said end flange and pressing said filter card against said end surface as ultrasonic energy is applied thereto.
 5. The method according to claim 1, including the step of positioning said chamber and said filter card on a jig with said end flange of said chamber in overlying relation to said filter card and with the opening in said filter card aligned with said discharge port, applying downward pressure to said cytology chamber against said filter to press said end flange against said filter card, and positioning an ultrasonic welding horn over said chamber with spaced energy applying end surfaces of said horn disposed in contact with one surface of said end flange opposite to said energy directors. 